IVR (interventional radiology) is for treating a human body from the inside of a blood vessel without incision of the human body by advancing a catheter inserted into the blood vessel from the femoral or forearm artery to a portion where an aneurysm or stenosis occurs in the brain or heart and placing a coil or a stent there, or advancing the catheter to a cancerous portion and dosing an embolic material or anticancer drug bringing about a high treatment effect with less invasion in comparison with other treatment methods, so that recently, IVR has produced successful results as a treatment method replacing operative treatments.
However, due to its longer X-ray fluoroscopy time and increased number of times of photography, the skin dose of a patient increased, and cases of serious skin lesions were reported.
To increase the safety and effectiveness of the IVR, it is necessary to prevent expression of deterministic effects as much as possible and lower the level of expression risk of the deterministic effect to an allowable level. Therefore, measurement of skin doses of patients, accumulation of data for a long period of time, and a proper feedback of exposure history to a medical site are necessary.
For this purpose, as described in “Patient's skin dose in IVR procedure using reflective dose measuring film,” Academic Journal of Japanese Society of Radiological Technology, Vol. 59-1 (January 2003), pp. 121-129, and “Report of Research on Patient's Exposure Dose and Protection in IVR,” Academic Journal of Japanese Society of Radiological Technology, Vol. 59-3 (March 2003), pp. 369-381, (1) laying of a dose measuring film between a medical bed and a patient and (2) attachment of a small-sized dosimeter to various points on the surface of a patient's body as described in, for example, Japanese Unexamined Patent Publication No. 2003-73137 (Patent Document 1), have been tried.
However, with the method (1) in which a film is laid under a patient, it is impossible to make completely closely contact with the patient's skin surface with the film, so that if the patient moves, correct values cannot be obtained. Furthermore, those measured by this method are only the X-ray doses transmitted through the film laid on the patient bed, so that the obtained values cannot accurately reflect radiation doses at various positions on the three-dimensional body surface of the patient according to X-rays that may be irradiated from various directions of the front, rear, left, and right sides.
On the other hand, the method (2) in which dosimeters are attached onto the surface of the patient's body requires a great deal of work of attaching a number of dosimeters one by one to the surface of the patient's body, and this obstructs actual medical activities, and dose measurement for a number of patients while covering the entire body surfaces in detail involves great difficulty even if it is performed as a clinical study.
At an actual medical site, the dosimeters are attached at 50 to 100 or more points on the surface of a patient's body, and it is necessary to satisfy the following requirements:
(1) Attachment of dosimeters should not obstruct treatment activities and the dosimeters can be attached and detached in about 5 minutes without pain to the patient.
(2) The dosimeters can be easily detached in case of rapid deterioration of the patient's condition.
(3) When attaching and detaching the dosimeters, they should be prevented from being broken or lost.
(4) Not only trained persons but also nurses and care staff can easily attach and detach the dosimeters.
(5) The dosimeters are radiolucent and do not obstruct treatment (X-ray fluoroscopy).
(6) The set positions of the dosimeters can be easily three-dimensionally reproduced.
(7) Doses can be easily analyzed.
(8) The dosimeters can be easily transported between a dosimeter service institution where doses are analyzed and a medical institution as a medical site.
(9) The blood and body fluids are likely to adhere to the dosimeters, and these should be prevented as much as possible from hindering all processes including dose analysis.
(10) Finally, it is necessary to analyze, accumulate, and trace several thousands through several tens of thousands of patient data, and the dosimeters can be sustainably used for the data in terms of cost as well.
(11) Furthermore, even when measurement is performed at different medical sites, it is preferable that measurement is performed at the same measuring positions in terms of data compiling.